<template>
  <div class="spec-preview">
    <img :src="skuImgeList[defaultIndex]?.imgUrl" />
    <div @mousemove="mousemove" class="event"></div>
    <div class="big">
      <img :src="skuImgeList[defaultIndex]?.imgUrl" ref="bigImgEle"/>
    </div>
    <div ref="maskEle" class="mask"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props: ["skuImgeList"],
  data() {
    return {
      defaultIndex: 0,
    };
  },
  mounted() {
    this.$bus.$on("getZoomIndex", (index) => {
      this.defaultIndex = index;
    });
  },
  methods: {
    mousemove(e) {
      //得到鼠标到外层边缘的距离
      const mouseToOut = {
        left: e.offsetX,
        top: e.offsetY,
      };

      //计算蒙版的位置
      const maskLoaction={
        x:mouseToOut.left-this.$refs.maskEle.offsetWidth/2,
        y:mouseToOut.top-this.$refs.maskEle.offsetHeight/2
      }

      //处理临界值
      if(maskLoaction.x<0){
        maskLoaction.x=0
      }else if(maskLoaction.x>=e.target.clientWidth-this.$refs.maskEle.offsetWidth){
        maskLoaction.x=e.target.clientWidth-this.$refs.maskEle.offsetWidth
      }
      if(maskLoaction.y<0){
        maskLoaction.y=0
      }else if(maskLoaction.y>=e.target.clientHeight-this.$refs.maskEle.offsetHeight){
        maskLoaction.y=e.target.clientHeight-this.$refs.maskEle.offsetHeight
      }

      //赋值
      this.$refs.maskEle.style.top=maskLoaction.y+'px'
      this.$refs.maskEle.style.left=maskLoaction.x+'px'

      //控制大图移动
      this.$refs.bigImgEle.style.left=-2*maskLoaction.x+'px'
      this.$refs.bigImgEle.style.top=-2*maskLoaction.y+'px'
    },
  },
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>